Multi-carbohydrase strategies improve the utilisation of wheat distiller's dried grains with solubles in broilers

Wheat distiller's dried grains with solubles (DDGS) are known for non-starch polysaccharide (NSP)-rich characteristics, limiting their use in poultry diets. This study evaluated whether enzyme supplementation enables higher inclusion of wheat DDGS in broiler diets. A total of 896 Cobb 500 mixed-sex broilers were assigned to 8 treatments in a 2 × 4 factorial arrangement with two levels of wheat DDGS (moderate: 60-108 g/kg; high: 187-224 g/kg) and four enzyme addition (none, xylanase+β-glucanase [XG], double-dose XG [XG 2 ×] or XG+β-mannanase [XG+M]) from d 0-35. During the starter phase (d0-10), birds fed the high wheat DDGS diet presented greater weight gain than those fed the moderate diet (P = 0.003); however, over d0-35, weight gain was reduced with the high wheat DDGS diet (P = 0.001). A wheat DDGS × enzyme interaction was observed for overall FCR (P < 0.001), where XG+M led to the most pronounced improvement in birds fed the high wheat DDGS diet but not in those fed the moderate diet. As main effects, the high wheat DDGS diet increased ileal digesta viscosity at d 35 (P < 0.001). All enzyme supplementation reduced ileal digesta viscosity at d 21 (P = 0.001) and d 35 (P = 0.025), and litter moisture at d 35 (P < 0.001). Ileal starch digestibility was improved (P = 0.016) by XG 2 × and XG+M compared with non-supplemented birds. In birds fed the moderate wheat DDGS diet, soluble NSP degradability was enhanced by XG 2 × compared with non-supplemented birds, whereas in birds fed the high wheat DDGS diet, it was improved by XG+M, leading to a significant interaction (P = 0.040). At the main effect level, total caecal short-chain fatty acid concentrations were higher in birds fed the high wheat DDGS diet (P = 0.020) and were increased by XG 2 × (P = 0.011). In summary, high wheat DDGS inclusion impaired growth performance, whereas XG+M mediated the greatest improvement in feed efficiency through enhanced soluble NSP degradation.